JP6273869B2 - Method for manufacturing molded body and method for manufacturing structure - Google Patents

Description

  The present invention relates to a method for manufacturing a molded body, a method for manufacturing a structure, and a workpiece.

Conventionally, a casting method, a forging method, a machining method, an electric discharge machining method, a laser machining method, a pressing method, a powder metallurgy method, etc. are known for producing a structure having a desired shape made of a metal material. Yes.
For example, Patent Document 1 discloses a method for manufacturing a metal frame, which is a superstructure of a dental implant, and includes a step of attaching a material to a 5-axis control machining center, and adjusting a processing position and inclination from one surface. A method is disclosed that includes processing a material and reversing the material and processing the material from the other side to produce a metal frame.
According to such a method, a highly accurate metal frame can be easily manufactured even if it is not an expert who has advanced technology.

On the other hand, depending on the application of the processed product, a material called difficult-to-process material or difficult-to-cut material that is difficult to process, such as cemented carbide, may be used as the metal material. When processing difficult-to-work materials with a machining center or the like, it is necessary to slow down the processing speed sufficiently. For this reason, it takes a long time to manufacture the metal frame, and there is a problem that the manufacturing efficiency is low.
In addition, since a difficult-to-process material is processed, there is a problem that the processing tool is quickly worn and the processing accuracy is likely to fluctuate.
Furthermore, a large amount of cutting oil is used to suppress friction between the processing tool and the material and to cool the processing tool and the material. For this reason, it is necessary to clean the metal frame after manufacture, resulting in a decrease in manufacturing efficiency and an increase in environmental load.

JP 2007-215854 A

  An object of the present invention is to provide a structure manufacturing method capable of easily manufacturing a structure having a target shape in a short time, and to easily form a molded body that becomes a structure having a target shape by firing. An object of the present invention is to provide a method for producing a molded body that can be manufactured, and a material to be cut that can be easily cut in a short time by being subjected to cutting.

The above object is achieved by the present invention described below.
In the method for producing a molded body of the present invention, a composition containing metal powder and a binder is pressure-molded to obtain a green compact having a relative density with respect to the true density of the constituent material of the metal powder of 70% or more and 90% or less. A compacting process;
Processing the green compact to obtain a molded body; and
It is characterized by having.
This makes it possible to achieve both high machinability and high shape retention in the green compact, so that it is possible to easily produce a molded body that becomes a target-shaped structure by firing in a short time. Can do.

In the manufacturing method of the molded object of this invention, it is preferable that the average particle diameter of the said metal powder is 1 micrometer or more and 15 micrometers or less.
Thereby, it is possible to obtain a green compact which can be processed more precisely and can efficiently cut out a molded body having a shape as designed.
In the method for producing a molded article of the present invention, the binder preferably contains polyvinyl alcohol having a saponification degree of 90 mol% or more and 98 mol% or less.
As a result, when the obtained green compact is subjected to a processing step, a green compact having a high green density can be obtained, and higher machinability can be imparted to the green compact. In such a green compact, the metal powder and the binder are uniformly dispersed inside, so that it is difficult for cracks to be generated or broken regardless of what kind of processing is performed.

In the method for producing a molded body of the present invention, the processing step includes:
A primary processing step of forming a processing mark penetrating the green compact leaving a part of the periphery of the region to be the molded body by performing a primary processing on the green compact;
Performing a secondary process on the green compact, thereby removing the part and separating the region from the green compact to obtain the molded body; and
It is preferable to have.
Thereby, a molded object can be handled in the state integrated with the green compact, without dropping out of a green compact in the middle of a primary processing process. For this reason, the position of the molded body can be maintained with respect to a point serving as a reference for the processing position of the green compact, and a decrease in the processing accuracy of the molded body in the primary processing step can be suppressed.

In the method for producing a molded body of the present invention, the part has a rod shape,
The partial minimum cross-sectional area is preferably 0.2 mm ² or more and 75 mm ² or less.
This prevents the molded body from dropping from the green compact in the primary processing step, and easily cuts the part in the secondary processing step, and prevents the molded body from being deformed at that time. can do.

The structure manufacturing method of the present invention is characterized in that the molded body obtained by the method of manufacturing a molded body of the present invention is fired to obtain a structure composed of a metal sintered body.
Thereby, the structure of the target shape can be manufactured easily in a short time.
The structure manufacturing method according to the present invention includes: performing a primary process on the green compact obtained by the method for manufacturing a molded body according to the present invention; Forming a processing mark penetrating the green compact leaving a part, and obtaining the molded body;
Firing the molded body to obtain a metal sintered body;
Removing the portion corresponding to the part of the sintered metal body to obtain a structure;
It is characterized by having.
Thereby, the structure of the target shape can be manufactured easily in a short time.

The work material to be cut of the present invention includes metal powder and a binder, and has a relative density of 70% or more and 90% or less with respect to the true density of the constituent material of the metal powder, and is used for cutting work. .
As a result, it is possible to obtain a workpiece to be cut that can be easily cut in a short time by being subjected to cutting. Therefore, by firing the molded body, a structure having a desired shape can be manufactured.

It is a perspective view which shows the green compact to which embodiment of the to-be-cut material of this invention is applied. It is a figure for demonstrating a mode that the green compact shown in FIG. 1 is processed, Comprising: It is a perspective view for demonstrating embodiment of the manufacturing method of the molded object of this invention. It is a figure for demonstrating the state in the middle of processing the green compact shown in FIG. 1, Comprising: It is a top view for demonstrating embodiment of the manufacturing method of the molded object of this invention. FIG. 4 is a sectional view taken along line AA in FIG. 3. FIG. 4 is a sectional view taken along line BB in FIG. 3. It is a figure for demonstrating a mode that the green compact shown in FIG. 1 is processed, Comprising: It is sectional drawing for demonstrating embodiment of the manufacturing method of the molded object of this invention. It is a figure for demonstrating a mode that the green compact shown in FIG. 1 is processed, Comprising: It is sectional drawing for demonstrating embodiment of the manufacturing method of the molded object of this invention. It is a figure which shows the molded object formed by processing the green compact shown in FIG. Fig.9 (a) is a figure which shows the sintered compact formed by baking the molded object shown in FIG. 8, Comprising: It is a top view which shows the structure manufactured by embodiment of the manufacturing method of the structure of this invention. FIG. 9B is a plan view showing the forceps obtained by assembling the structure shown in FIG. Sample No. It is a photograph which shows the state after giving primary processing to the green compact in manufacture of 1 structure. Sample No. It is a photograph which shows the forceps obtained by manufacture of 1 structure.

Hereinafter, the manufacturing method of a molded object, the manufacturing method of a structure, and a workpiece to be cut according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a perspective view showing a green compact to which an embodiment of a workpiece to be cut according to the present invention is applied. FIG. 2 is a view for explaining a state of processing the green compact shown in FIG. 1, and is a perspective view for explaining an embodiment of a method for producing a molded body of the present invention. FIG. 3 is a view for explaining a state in the middle of processing the green compact shown in FIG. 1, and is a plan view for explaining an embodiment of the method for producing a molded body of the present invention. 4 is a cross-sectional view taken along line AA in FIG. 5 is a cross-sectional view taken along line BB in FIG. 6 and 7 are views for explaining a state of processing the green compact shown in FIG. 1, respectively, and are cross-sectional views for explaining an embodiment of a method for producing a molded body of the present invention. FIG. 8 is a view showing a molded body obtained by processing the green compact shown in FIG. Fig.9 (a) is a figure which shows the sintered compact formed by baking the molded object shown in FIG. 8, Comprising: It is a top view which shows the structure manufactured by embodiment of the manufacturing method of the structure of this invention. FIG. 9B is a plan view showing the forceps obtained by assembling the structure shown in FIG.
In the following description, for convenience of explanation, the upper side of FIGS. 4 and 5 is referred to as “upper” and the lower side is referred to as “lower”.

[Method for producing molded article]
The method for producing a molded body according to the present embodiment includes a compacting process for pressing a composition containing a metal powder and a binder to obtain a compact 1 shown in FIG. 2 is processed using a processing tool 5 as shown in FIG. 2 to obtain a molded body 2 shown in FIG. The molded body 2 thus obtained becomes a sintered body by being fired by being subjected to a structure manufacturing method described later. This sintered body has a shape reflecting the shape of the molded body with high accuracy, and can be used as the structure 3 as shown in FIG. Hereinafter, each process will be described sequentially.

[1] Compacting Step First, a composition containing a metal powder and a binder is pressure-molded to obtain a compact 1 (an embodiment of the workpiece to be cut according to the present invention). The green compact 1 is used to cut out a molded body 2 having a desired shape by being subjected to a molded body processing step described later. That is, the green compact 1 has both mechanical strength and workability that can withstand cutting.

[1-1] Preparation of composition First, a composition containing a metal powder and a binder is prepared. This composition mainly contains a metal powder and a binder.
(Metal powder)
The metal powder is a powder of a metal material. The metal material is not particularly limited and may be any material as long as it can be sintered. For example, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, In, Sn, Sb, Hf, Ta, W, Ir, Pt , Au, Pb, Bi and the like, or alloys containing these elements. Further, the metal powder may be a mixed powder obtained by mixing two or more kinds of powders having different compositions from each other, or may be a mixed powder of a metal powder and a ceramic powder.

Among these, examples of the Fe-based alloy include stainless steel, low carbon steel, carbon steel, heat resistant steel, die steel, high speed tool steel, Fe—Ni alloy, Fe—Ni—Co alloy, and the like.
Examples of the Ni-based alloy include Ni-Cr-Fe-based alloys, Ni-Cr-Mo-based alloys, Ni-Fe-based alloys, and the like.
Examples of the Co-based alloy include a Co-Cr-based alloy, a Co-Cr-Mo-based alloy, and a Co-Al-W-based alloy.
Examples of Ti-based alloys include alloys of Ti and metal elements such as Al, V, Nb, Zr, Ta, and Mo. Specifically, Ti-6Al-4V, Ti-6Al— 7Nb and the like.
Examples of the Al-based alloy include duralumin.

  Examples of the ceramic material constituting the ceramic powder include oxides such as alumina, magnesia, beryllia, zirconia, yttria, forsterite, steatite, wollastonite, mullite, cordierite, ferrite, sialon, and cerium oxide. Examples thereof include ceramic materials, non-oxide ceramic materials such as silicon nitride, aluminum nitride, boron nitride, titanium nitride, silicon carbide, boron carbide, titanium carbide, and tungsten carbide.

  It should be noted that so-called difficult-to-process materials may be included in the materials as described above. In the present invention, the structure 3 having a desired shape can be manufactured regardless of the workability of the metal material or the ceramic material itself. For this reason, by using the metal powder of difficult-to-process materials, various structures 3 of difficult-to-process materials that have been difficult to manufacture by the conventional method can be easily manufactured. At that time, a structure with high dimensional accuracy can be manufactured regardless of the shape of the structure 3, which is useful in that a structure with high added value can be manufactured.

The average particle size of the metal powder is preferably about 1 μm to 15 μm, and more preferably about 2 μm to 10 μm. By using the metal powder having such an average particle size, the green compact 1 can be processed more precisely, and a molded body having a shape as designed can be efficiently cut out. That is, when the average particle size of the metal powder is below the lower limit value, the mechanical strength of the whole green compact 1 is lowered, so that depending on the size and shape of the molded body cut out in the molded body processing step described later, There is a possibility that the target green compact 1 may crack or collapse. Moreover, since the filling property of a metal powder falls, the content rate of the metal powder in the green compact 1 falls. Thereby, when the molded body cut out from the green compact 1 is fired in a firing step described later, the shrinkage rate is increased, and the dimensional accuracy of the sintered body may be reduced. On the other hand, if the average particle size of the metal powder exceeds the upper limit, the probability that the processing tool will hit the metal powder particles in the molded body processing step, which will be described later, increases, and the flatness of the processed surface is likely to be damaged. Depending on the shape of the molded product, the dimensional accuracy of the molded product may be reduced.
The average particle size of the metal powder is a particle size when the accumulation of the mass-based particle size is 50% from the small diameter side in the particle size distribution obtained by the laser diffraction method.

The maximum particle size of the metal powder is preferably about 10 μm to 100 μm, and more preferably about 10 μm to 50 μm. By using the metal powder having such a maximum particle size, the filling property of the metal powder in the green compact 1 can be particularly enhanced. As a result, it is possible to cut out the molded body 2 with high processing accuracy in the molded body processing step and excellent flatness of the processed surface. In addition, since this high filling property is mainly influenced by how the particles of the metal powder are packed, the average particle size of the metal powder is set within the above range, and the maximum particle size is set within the above range. Thus, it is considered that this characteristic is obtained due to the particularly good clogging between the particles.
The maximum particle size of the metal powder is the particle size when the cumulative particle size based on mass is 99.9% from the small diameter side in the particle size distribution obtained by the laser diffraction method.

  Furthermore, the average particle size of the metal powder is D50, and the particle size distribution when the accumulation of the mass-based particle size is 10% from the small diameter side in the particle size distribution obtained by the laser diffraction method for the metal powder is D10. (D90−D10) / D50 is preferably 0.5 or more and 5 or less, and more preferably 1.0 or more and 3.5 or less, when the particle size at 90% to 90% is D90. The metal powder satisfying such conditions is particularly useful from the viewpoint of the filling property of the metal powder in the green compact 1. That is, since the metal powder satisfying such conditions has a relatively narrow particle size distribution, it becomes possible to apply a more uniform compressive force to the entire green compact 1 during compacting. For this reason, in the green compact 1 obtained, the density becomes more uniform, and the variation of the residual stress at the time of the green compact is suppressed to be small. As a result, the molded bodies 21 and 22 are less likely to be deformed with the release of stress in the molded body processing step described later, and the shrinkage rate during sintering described later becomes more uniform. Degradation can be minimized.

Moreover, as metal powder, what was manufactured by various powdering methods, such as an atomizing method (for example, a water atomizing method, a gas atomizing method, a high-speed rotation water stream atomizing method etc.), a reduction method, a carbonyl method, a pulverization method, is used, for example. It is done.
Of these, those manufactured by the atomizing method are preferably used, and those manufactured by the water atomizing method or the high-speed rotating water atomizing method are more preferably used. The atomizing method is a method for producing a metal powder by causing molten metal (molten metal) to collide with a fluid (liquid or gas) jetted at high speed, thereby pulverizing and cooling the molten metal. By producing metal powder by such an atomizing method, extremely fine powder can be efficiently produced. Moreover, the particle shape of the obtained powder becomes close to a spherical shape due to the effect of surface tension. For this reason, when the composition containing such a metal powder is pressure-molded into the green compact 1, the green compact 1 with a high filling rate is obtained.

Further, when the short diameter of the metal powder particles is S [μm] and the long diameter is L [μm], the average aspect ratio defined by S / L is about 0.4 or more and 1 or less. Is preferable, and it is more preferably about 0.6 or more and 0.9 or less. Since the metal powder having such an aspect ratio has a relatively nearly spherical shape, the filling rate when compacted is increased. As a result, the relative density of the green compact 1 can be optimized.
The major axis is the maximum length that can be taken in the projected image of the particle, and the minor axis is the maximum length in a direction orthogonal to the maximum length. Then, the aspect ratio is obtained for 100 particles, and the average value is defined as the “average aspect ratio” described above.

The tap density of the metal powder is preferably 3.5 g / cm ³ or more, and more preferably 4 g / cm ³ or more. When the metal powder has such a large tap density, the packing property between the particles is particularly high when the green compact 1 is obtained. For this reason, finally, the green compact 1 with which the relative density was optimized can be obtained. In addition, an upper limit is not specifically limited, For example, even the true density of metal powder is accept | permitted.

(binder)
Examples of the binder include polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymers, acrylic resins such as polymethyl methacrylate and polybutyl methacrylate, styrene resins such as polystyrene, polyvinyl chloride, polyvinylidene chloride, and polyamides. Various resins such as polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyethers, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone or copolymers thereof, polysaccharides such as methyl cellulose, ethyl cellulose and hydroxyethyl cellulose, higher fatty acid esters, higher Examples include various organic binders such as fatty acid amides, and one or more of these can be used in combination.

  The content of the binder in the green compact 1 is naturally determined according to the relative density of the green compact 1, the composition of the metal powder, and the like, but is preferably about 10% by volume to 70% by volume as an example. It is more preferable that the volume is not less than about volume% and not more than 60 volume%. If the content rate of a binder exists in the said range, when the compact 1 is used for the molded object processing process mentioned later, high machinability can be obtained. That is, when the binder content falls below the lower limit, the amount of binder interposed between the metal powder particles is reduced, so that the binding force between the metal powder particles is weakened, and the green compact 1 is processed during processing. May be deformed. On the other hand, when the content rate of the binder exceeds the upper limit value, the content rate of the metal powder in the green compact 1 is relatively lowered. For this reason, the shrinkage | contraction rate at the time of sintering of a molded object becomes large, and there exists a possibility that the dimensional accuracy of a sintered compact may fall.

  Among these, the binder is preferably composed mainly of at least one of polyvinyl alcohol and acrylic resin, and more preferably composed of a mixture of both. A binder mainly composed of such components can particularly improve the machinability of the green compact 1. That is, the green compact 1 containing such a binder has a particularly high workability (machinability) with a processing tool when subjected to a molded body processing step described later, and is therefore easy to process into a shape as designed. Become. As a result, a molded body having a shape as designed can be cut out particularly efficiently.

  The content of polyvinyl alcohol and the content of acrylic resin in the binder are each preferably 5% by mass or more and 100% by mass or less, and more preferably 10% by mass or more and 95% by mass or less. By setting the content of polyvinyl alcohol and the content of acrylic resin within the above ranges, both the machinability and shape retention of the green compact 1 can be achieved. For this reason, the shape as designed can be cut out from the green compact 1, and a molded body with higher dimensional accuracy can be obtained.

  Moreover, when using together polyvinyl alcohol and acrylic resin, when the content rate of acrylic resin is set to 1, it is preferable that the content rate of polyvinyl alcohol is 0.2 or more and 5 or less by mass ratio, 0 More preferably, it is 5 or more and 3 or less. By setting the mixing ratio of the polyvinyl alcohol and the acrylic resin within the above range, the machinability and the shape retention of the green compact 1 can be made more highly compatible. A highly accurate molded body can be cut out.

In this case, a copolymer obtained by copolymerizing polyvinyl alcohol and an acrylic resin may be used. By using such a copolymer, the effect of the combined use as described above becomes more remarkable, and the homogeneity of the green compact 1 becomes particularly high, which contributes to the improvement of the dimensional accuracy of the molded body.
Examples of such a copolymer include a copolymer obtained by copolymerizing an acrylic resin with partially saponified polyvinyl alcohol.

Among these, as the polyvinyl alcohol, those having a saponification degree of 90 mol% or more and 98 mol% or less are preferably used, and those having a saponification degree of 92 mol% or more and 94 mol% or less are more preferably used. Such polyvinyl alcohol contributes to imparting higher machinability to the green compact 1 when the green compact 1 is subjected to a molded body processing step described later. The reason for this effect is not clear, but one reason is that the hydroxyl group content of polyvinyl alcohol is optimized when the saponification degree of polyvinyl alcohol is within the above range. That is, when the hydroxyl group content is optimized, when the metal powder is granulated, polyvinyl alcohol is easily interposed between the metal particles, and the granulation property is improved. This is presumably because the strength of the hydrogen bond between the metal powder and the polyvinyl alcohol is increased by optimizing the hydroxyl group content. Thus, when granulation property becomes high, the granulated powder with uniform particle size distribution can be manufactured easily, and by using such granulated powder, the green compact 1 with uniform and high compaction density is obtained. be able to. In such a green compact 1, the metal powder and the binder are uniformly dispersed inside, so that it is difficult for cracks to be generated or to be broken no matter what kind of processing is performed.
In addition, the saponification degree of the polyvinyl alcohol mentioned above is measured based on the method prescribed | regulated to JISK6726.

As the polyvinyl alcohol, those having a degree of polymerization of about 100 or more and 3000 or less are preferably used, and those having a degree of polymerization of about 200 or more and 2500 or less are more preferably used. Such polyvinyl alcohol can enhance the binding property between the particles of the metal powder by the binder when the green compact 1 is subjected to a molded body processing step described later. Contributes to imparting high machinability. Moreover, the solubility with respect to the polar solvent of polyvinyl alcohol becomes favorable because a polymerization degree exists in the said range. For this reason, when the metal powder is granulated in the production of the green compact 1, the binder containing polyvinyl alcohol is granulated while uniformly adhering around the metal powder particles. can get. The green compact 1 makes it possible to cut out a molded body having a shape as designed regardless of what kind of processing is performed.
In addition, the polymerization degree of the polyvinyl alcohol mentioned above is measured based on the method prescribed | regulated to JISK6726.

Further, in the green compact 1, various additives such as a dispersant, a lubricant, a plasticizer, an antioxidant, a rust inhibitor, a surfactant, and a degreasing accelerator, as necessary, in addition to the metal powder and the binder. May be added. In this case, the total amount of these additives is preferably set to be 10% by mass or less in the green compact 1.
Among these, examples of the plasticizer include phthalic acid esters (eg, DOP, DEP, DBP), adipic acid esters, trimellitic acid esters, sebacic acid esters, and the like. Can be mixed and used.

Examples of the lubricant include waxes, higher fatty acids, alcohols, fatty acid metals, nonionic surfactants, silicone-based lubricants, and the like, and one or a mixture of two or more thereof is used.
Among these, as waxes, for example, plant wax such as candelilla wax, carnauba wax, rice wax, wax, jojoba oil, animal wax such as beeswax, lanolin, spermaceti, montan wax, ozokerite, Mineral wax such as ceresin, paraffin wax, microcrystalline wax, natural wax such as petroleum wax such as petrolatum, synthetic hydrocarbons such as polyethylene wax, montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives Modified wax, hydrogenated wax such as hydrogenated castor oil, hydrogenated castor oil derivative, fatty acid such as 12-hydroxystearic acid, acid amide such as stearamide, esthetic such as phthalimide anhydride Synthetic waxes and the like.

Examples of higher fatty acids include stearic acid, oleic acid, linoleic acid and the like, and saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid are particularly preferably used.
Examples of alcohols include polyhydric alcohols, polyglycols, polyglycerols, and the like, and cetyl alcohol, stearyl alcohol, oleyl alcohol, mannitol, and the like are particularly preferably used.

  Examples of the fatty acid metal include lauric acid, stearic acid, succinic acid, stearyl lactic acid, lactic acid, phthalic acid, benzoic acid, hydroxystearic acid, ricinoleic acid, naphthenic acid, oleic acid, palmitic acid, and erucic acid. Examples include compounds of higher fatty acids and metals such as Li, Na, Mg, Ca, Sr, Ba, Zn, Cd, Al, Sn, Pb, and Cd. In particular, magnesium stearate, calcium stearate, sodium stearate Zinc stearate, calcium oleate, zinc oleate, magnesium oleate and the like are preferably used.

Examples of nonionic surfactant-based lubricants include Electro Stripper TS-2, Electro Stripper TS-3 (both manufactured by Kao Corporation), and the like.
Examples of the silicone-based lubricant include dimethylpolysiloxane and modified products thereof, carboxyl-modified silicone, α-methylstyrene-modified silicone, α-olefin-modified silicone, polyether-modified silicone, fluorine-modified silicone, hydrophilic specially-modified silicone, and olefin polysiloxane. Examples include ether-modified silicone, epoxy-modified silicone, amino-modified silicone, amide-modified silicone, and alcohol-modified silicone.

  Among these, the composition preferably contains a lubricant as an additive, and preferably contains at least one of a higher fatty acid and a fatty acid metal. These additives can particularly enhance the lubricity between the particles of the metal powder and can particularly suppress the adverse effect on the binder. For this reason, the machinability which the binder mentioned above brings can be improved more. That is, when the green compact 1 is processed with a processing tool by increasing the lubricity between the particles of the metal powder by the lubricant, the frictional resistance between the particles of the metal powder and the frictional resistance between the processing tool and the particles of the metal powder. And the occurrence of unintended deformation (cracking, collapse, etc.) of the green compact 1 due to processing can be suppressed. Therefore, the green compact 1 containing such a lubricant makes it possible to cut out a molded body having a shape as designed particularly efficiently when subjected to a molded body processing step described later.

Furthermore, the composition for producing the green compact 1 may contain a solvent as necessary. The solvent is not particularly limited as long as it can dissolve or disperse the binder, but water, and organic solvents such as terpineol, butyl carbitol, acetone, toluene and the like are used.
Further, this composition may be in the form of a granulated powder obtained through a granulation process, or in the form of a kneaded product obtained through a kneading process, if necessary. May be. These forms are appropriately selected according to the molding method of the composition to be described later.

Among these, although the average particle diameter of granulated powder is not specifically limited, It is preferable that they are 10 micrometers or more and 300 micrometers or less, and it is more preferable that they are 30 micrometers or more and 150 micrometers or less. Thereby, in manufacture of the compact 1 mentioned later, it becomes easy to apply a pressurizing force to granulated powder. As a result, a green compact 1 excellent in ease of processing and shape retention can be obtained.
The average particle size of the granulated powder is the particle size when the cumulative particle size based on mass is 50% from the small diameter side in the particle size distribution obtained by the laser diffraction method.
Furthermore, the average particle size of the granulated powder is preferably 2 to 30 times, more preferably 3 to 20 times the average particle size of the metal powder contained therein. By setting the average particle size of the granulated powder within the above range, it is possible to further improve the ease of processing and shape retention of the green compact 1.

[1-2] Manufacture of a green compact Next, the prepared composition is pressure-molded to obtain a green compact 1.
The molding method is not particularly limited, and examples thereof include a press molding method, an extrusion molding method, and an injection molding method.
Molding pressure in the press molding is preferably in the range of about more than 10 MPa 1000 MPa or less (0.1 t / cm ² or more 10t / cm ² or less), more preferably to or higher than 300MPa or less 50 MPa.
Further, the molding temperature in the press molding method is preferably about 20 ° C. or higher and 70 ° C. or lower as the temperature of the composition.

Molding pressure in the extrusion molding method is preferably in the range of about more than 10 MPa 500 MPa or less (0.1 t / cm ² or more 5t / cm ² or less), more preferably to or higher than 200MPa or less 50 MPa.
Further, the molding temperature in the extrusion molding method is preferably about 80 ° C. or more and 210 ° C. or less as the temperature of the composition.

Molding pressure in the injection molding method is preferably in the range of about more than 10 MPa 500 MPa or less (0.1 t / cm ² or more 5t / cm ² or less), more preferably to or higher than 200MPa or less 50 MPa.
The molding temperature in the injection molding method is preferably about 80 ° C. or more and 210 ° C. or less as the temperature of the composition.

  By setting the molding pressure and molding temperature within the above ranges, a green compact 1 having a high relative density and excellent mechanical properties can be obtained. That is, when the particles of the metal powder are appropriately packed, the mechanical properties of the green compact 1 become sufficiently high, and the green compact 1 that can withstand a molded body processing step described later is obtained. Moreover, the binder is melted by the molding temperature and then solidified by being cooled, whereby the particles of the metal powder are fixed via the binder. From this point of view, the mechanical properties of the green compact 1 can be enhanced. And by processing such a green compact 1, the molded object 2 with high dimensional accuracy can be efficiently cut out.

Here, the green compact 1 containing a metal powder, a binder, or the like is affected by machinability and shape retention in the molded body processing step depending on the green compact state.
The inventor has intensively studied the balance between the machinability and the shape retention. And when the relative density of the green compact 1 is set to 70% or more and 90% or less, it has been found that the green compact 1 can achieve both high machinability and high shape retention, thereby completing the present invention. It was.

That is, when the relative density of the green compact 1 is lower than the lower limit, the metal powder and binder filling properties of the green compact 1 may be reduced, or the metal powder content in the green compact 1 may be reduced. Therefore, as a result, there is a possibility that the green compact 1 is likely to be deformed in the molded body processing step, or the contraction rate of the molded body 2 is likely to be greatly deformed during sintering. On the other hand, if the relative density of the green compact 1 exceeds the upper limit, the stress during compaction tends to remain in the green compact 1 or the binder content in the green compact 1 is low and mechanical. Since the strength may be lowered, as a result, the residual stress in the green compact 1 is released in the green body processing step, and the green compact 1 is likely to be deformed, or interference with the processing tool. Therefore, the green compact 1 may be easily deformed.
The relative density of the green compact 1 is obtained by measuring the density of the green compact 1 and calculating the relative value of this density with respect to the true density of the constituent material of the metal powder.

The shape of the green compact 1 is not particularly limited, and may be, for example, a rectangular parallelepiped, a cube, a sphere, a polygonal column, or the like, but the green compact 1 shown in FIG. ). The green compact 1 having such a shape is more uniform because the compressive force at the time of compacting is easily applied to the composition. For this reason, by using the compact 1 having a disc shape, the molded body 2 having a target shape can be efficiently cut out.
In the molded body processing step to be described later, by performing processing on the main surface 11 and the main surface 12 (see FIG. 1) corresponding to the two bottom surfaces of the cylinder in the compact 1 having a disc shape, An example of cutting out the molded body 2 will be described.

[2] Molded Body Processing Step Next, as shown in FIG. 2, the obtained green compact 1 is machined (molded body processing step). Thereby, the target shape is cut out from the green compact 1. In the present embodiment, as an example, a case where two molded bodies 21 and 22 as shown in FIG. 3 are cut out will be described. In the present specification, these two molded bodies 21 and 22 may be collectively referred to as “molded body 2”.
In this molded body processing step, the molded body 2 may be cut out from the green compact 1 by a single machining, but in the present embodiment, the molded body processing step is referred to as “primary processing step”. ”And“ secondary processing step ”will be described.

[2-1] Primary processing step First, primary processing is performed on the green compact 1 shown in FIG. 1 (primary processing step).
A green compact 1 shown in FIG. 3 shows a state in the middle of the compact processing step, that is, after the primary processing step, and the two compacts 21 and 22 cut into the compact 1 are Finally, two structures constituting the forceps used as a surgical instrument are obtained. When these structures are assembled, they become forceps in the form of “scissors” that can be freely opened and closed.

In the green compact 1 shown in FIGS. 3 to 5, a processing mark 26 that penetrates the green compact 1 and a non-penetrating process mark 27 are formed so as to surround the two compacts 21 and 22. Has been. In the primary processing step, the formed body 2 having a desired shape is cut out by forming such processing marks 26 and 27 by machining.
In addition, when the molded bodies 21 and 22 are completely surrounded by the processing marks 26, the molded bodies 21 and 22 are detached from the green compact 1. Therefore, in order to prevent this, in the primary processing step, Around the two molded bodies 21 and 22, a part without the processing mark 26 is provided. This portion is a connecting portion 25 that connects the compacts 21 and 22 and the green compact 1. By providing such a connecting portion 25, the molded bodies 21 and 22 are handled in an integrated state with the green compact 1 without dropping from the green compact 1 during the primary processing step. . For this reason, the position of the compacts 21 and 22 can be maintained with respect to the reference point of the processing position of the green compact 1, and a reduction in processing accuracy of the compacts 21 and 22 in the primary processing step can be suppressed. be able to. Alternatively, the formed marks 21 and 22 may be surrounded by the processed marks 27 without forming the processed marks 26. In this case, although the volume which should be processed by the secondary processing process mentioned later increases, the fall of the processing precision of the molded objects 21 and 22 in primary processing can be suppressed more.

  3 to 5 is formed into a long and narrow bar shape by forming a processing mark 27 that does not penetrate the green compact 1, and between the compacts 21 and 22 and the green compact 1. Are connected with a small cross-sectional area. For this reason, in the secondary processing step, the connecting portion 25 can be cut with a weak force. As a result, the molded bodies 21 and 22 can be separated from the green compact 1 while preventing the molded bodies 21 and 22 from being deformed or broken with the cutting operation of the connecting portion 25.

  Also, a plurality of connecting portions 25 shown in FIG. 3 are provided at regular intervals along the periphery of the molded bodies 21 and 22. Thereby, since the load of each molded object 21,22 is disperse | distributed to each connection part 25, the bending of each connection part 25, the deformation | transformation of each molded object 21,22, etc. will be suppressed. The intervals at which the connecting portions 25 are provided around the compacts 21 and 22 are appropriately determined according to the thickness and size of the compacts 21 and 22, the minimum cross-sectional area of the connecting portions 25, the relative density of the green compact 1, and the like. Although it is set, it is about 1 mm or more and 50 mm or less as an example.

In addition, the shape of each connection part 25 shown in FIG. 3 is an example, and what kind of shape may be sufficient as it. For example, the cross-sectional shape of each connecting portion 25 may be circular, polygonal, or other shapes. In that case, the minimum cross-sectional area of each connecting portion 25 is preferably at 0.2 mm ² or more 75 mm ² or less, more preferably 0.5 mm ² or more 50 mm ² or less. By setting the minimum cross-sectional area of each connecting portion 25 within the above range, while preventing the molded bodies 21 and 22 from dropping from the green compact 1 in the primary processing step, It is possible to easily cut each connecting portion 25 and prevent deformation of the molded bodies 21 and 22 at that time.

  That is, when the minimum cross-sectional area of each connection part 25 is less than the lower limit, the mechanical strength of each connection part 25 becomes insufficient, the connection part 25 breaks, and depending on the shape of the molded bodies 21 and 22 There is a risk that deformation will occur along with this. On the other hand, when the minimum cross-sectional area of each connecting portion 25 exceeds the upper limit, each connecting portion 25 becomes difficult to cut in the secondary processing step described later, and the molded bodies 21 and 22 are deformed during the cutting operation. May be accompanied.

  In consideration of the work efficiency in the secondary processing step described later, it is preferable that the number of connecting portions 25 provided in each of the molded bodies 21 and 22 is as small as possible, and the minimum cross-sectional area of each connecting portion 25 is as small as possible. However, when considering the ease of deformation of the molded bodies 21 and 22 during the primary processing step, the number of connecting portions 25 provided in each of the molded bodies 21 and 22 is as large as possible, and the minimum of each connecting portion 25 is provided. Since the cross-sectional area should be as large as possible, the number of connecting portions 25 and the minimum cross-sectional area may be determined based on these.

4 is a cross-sectional view taken along the line AA of FIG. 3, and each connecting portion 25 has an elongated rod shape having a long axis parallel to the main surfaces 11 and 12 of the green compact 1, and its length. L is appropriately set according to the diameter of the processing tool, but is preferably about 0.1 mm or more and 10 mm or less, and more preferably about 0.5 mm or more and 8 mm or less.
The thickness t of each connecting portion 25 is preferably set to about 5% or more and 90% or less of the length L, and more preferably set to about 10% or more and 80% or less. Thereby, each connection part 25 has sufficient mechanical strength to support each molded object 21,22.

A line AA in FIG. 3 is drawn along the long axis of the connecting portion 25, and a line BB is drawn so as to cross the machining mark 26.
FIG. 5 is a cross-sectional view taken along the line BB of FIG. 5. In the portion where the connecting portion 25 is not provided, the molded body 2 is isolated from the green compact 1 through the processing marks 26. Therefore, in the green compact 1 shown in FIG. 3, the molded bodies 21 and 22 cut out by forming the processing marks 26 can be obtained by simply cutting the connecting portion 25 in the secondary processing step while maintaining high dimensional accuracy. It can be separated from the powder 1.

  When the green compact 1 is subjected to primary processing, the green compact 1 is usually placed so that one of the main surfaces 11 and 12 is in contact with the upper surface of the stage of the processing apparatus. . For this reason, in the primary processing, in order to form the processing traces 26 and 27 having the cross-sectional shapes as shown in FIGS. 4 and 5, for example, as shown in FIG. After that, the front and back of the green compact 1 may be reversed, and processing may be performed from the main surface 12 side as shown in FIG. If it does in this way, in the case of primary processing, also about the part which is hidden behind the compacts 21 and 22, processing can be performed.

  However, depending on the method of holding the green compact 1, the reversing operation of the green compact 1 may be unnecessary. For example, when there is a region that is not used for forming the compacts 21 and 22, such as the outer peripheral portion of the green compact 1, by holding only that region, replacement work such as reversal of the green compact 1 is not performed. The next processing step can be performed. In this case, a machining apparatus capable of multi-axis control is preferably used.

  Any processing apparatus can be used for the primary processing. For example, a machining center, a milling machine, a drilling machine, a lathe, etc. are mentioned. Among these, a processing apparatus provided with a CAM (computer aided manufacturing) system is preferably used. In the CAM system, it is possible to perform precise processing so that a model designed by a CAD (computer aided design) system can be faithfully reproduced. For this reason, even if it is not an expert engineer etc., it is useful at the point that the molded objects 21 and 22 close | similar to the target shape can be cut out efficiently.

[2-2] Secondary processing step Next, secondary processing is performed on the green compact 1 after the primary processing step (secondary processing step).
FIG. 8 shows a state of the formed bodies 21 and 22 obtained by the formed body processing step, that is, the secondary processing step.
The molded bodies 21 and 22 shown in FIG. 8 are obtained by the secondary process of cutting and removing each connecting portion 25 shown in FIG. Although these connection parts 25 are comprised with the green compact containing a metal powder, they have a mechanical characteristic required and sufficient to support the compacts 21 and 22, and they are also highly plastic. This is because the mechanical properties of the green compact 1 including the connecting portion 25 are mainly due to the force of binding the metal powder particles by the binder and the frictional resistance between the metal powder particles. It is thought that the effect. Therefore, it is relatively easy to cut and remove the connecting portion 25, and the trace of removing the connecting portion 25 has an advantage that it is easy to obtain a smooth surface. That is, the molded bodies 21 and 22 with high dimensional accuracy can be separated from the green compact 1 with almost no influence from the removal of the connecting portion 25.
In addition, since the secondary processing for cutting and removing the connecting portion 25 has a small force required for processing and the volume to be processed is limited, in addition to processing by the processing apparatus as described above, It can also be done manually.

As mentioned above, although the molded object processing process was demonstrated, the number which divides a process in a molded object processing process is not limited to 2 times mentioned above, You may divide into 3 times or more.
In addition, since the molded body 2 shrinks in the firing step described later, in the final molded body processing step, the molded body is designed so that the sintered body has a desired shape and size based on the amount of shrinkage. The shape and size of 2 are appropriately set.

[Method of manufacturing structure]
<< First Embodiment >>
First, a first embodiment of the structure manufacturing method of the present invention will be described.
The structure manufacturing method according to the present embodiment includes a step of firing the molded body 2 manufactured by the method for manufacturing a molded body according to the above-described embodiment to obtain a sintered body. In this way, the structure 3 shown in FIG. 9 is obtained.

[1] Firing step First, prior to firing, the molded body 2 may be subjected to a degreasing treatment. A degreased body is obtained by performing a degreasing treatment (debinding treatment).
Specifically, degreasing treatment is performed by heating the molded body 2 to decompose the binder and removing it from the molded body 2.
As this degreasing process, the method of heating the molded object 2, the method of exposing the molded object 2 to the gas which decomposes | disassembles a binder, etc. are mentioned, for example.

When the method of heating the molded body 2 is used, the heating condition of the molded body 2 is about 100 ° C. or higher and 750 ° C. or lower × 0.1 hour or longer and 20 hours or shorter, although it varies slightly depending on the composition and blending amount of the binder. It is preferably 150 ° C. or more and 600 ° C. or less × more preferably 0.5 hours or more and 15 hours or less. Thereby, the degreasing | defatting of the molded object 2 can be performed sufficiently and necessary, without sintering the molded object 2. FIG. As a result, it is possible to prevent a large amount of the binder component from remaining inside the degreased body.
Further, the atmosphere for heating the molded body 2 is not particularly limited, and a reducing gas atmosphere such as hydrogen, an inert gas atmosphere such as nitrogen and argon, an oxidizing gas atmosphere such as air, or these And a reduced-pressure atmosphere obtained by reducing the atmosphere.
On the other hand, examples of the gas that decomposes the binder include ozone gas.
Such a degreasing process is divided into a plurality of steps (steps) having different degreasing conditions, so that the binder in the molded body 2 is decomposed and removed more quickly and not to remain in the molded body 2. can do.

Moreover, you may make it perform machining, such as cutting, grinding | polishing, and cutting | disconnection with respect to a degreased body as needed. Since the degreased body is relatively low in hardness and relatively rich in plasticity, it can be easily machined while preventing the shape of the degreased body from collapsing. According to such machining, a sintered body with high dimensional accuracy can be easily obtained finally.
In addition, when there are few binder amounts in the molded object 2, since it may serve as a degreasing process in the baking processing mentioned later, in that case, a degreasing process can be abbreviate | omitted.

Next, the degreased body (or molded body 2) is subjected to a firing treatment.
Due to this firing, the metal powder in the degreased body is diffused at the interface between the particles, resulting in sintering. Thereby, the sintered compact of metal powder is obtained and the structure 3 is obtained.
The firing temperature varies depending on the composition, particle size, and the like of the metal powder used for manufacturing the molded body 2, but is set to about 980 ° C. or higher and 1330 ° C. or lower as an example. The temperature is preferably about 1050 ° C. or higher and 1260 ° C. or lower.
The firing time is 0.2 hours or more and 7 hours or less, and preferably 1 hour or more and 6 hours or less.
In the firing step, the sintering temperature or a firing atmosphere described later may be changed during the firing process.
By setting the firing conditions in such a range, the entire defatted body can be sufficiently sintered while preventing oversintering due to excessive progress of sintering and enlargement of the crystal structure. As a result, a sintered body having a high density and excellent mechanical properties can be obtained.

Further, the atmosphere during firing is not particularly limited, but in consideration of preventing significant oxidation of the metal powder, a reducing gas atmosphere such as hydrogen, an inert gas atmosphere such as argon, or these atmospheres The reduced pressure atmosphere etc. which reduced pressure is preferably used.
Of the structures 3 shown in FIG. 9, the structure 3 shown in FIG. 9A is obtained by firing the molded body 2, and the structure 3 shown in FIG. 9B is shown in FIG. The structure 3 shown in FIG. 4 is an assembled forceps that is one of the surgical tools.

  As described above, according to the structure manufacturing method of the present invention, the green compact 1 having the desired shape is cut by processing the green compact 1 in which the metal powder particles are bound together with the binder. The sintered body (structure 3) having a target shape is obtained by firing and firing. For this reason, compared with the case where a metal material is processed, the processing operation can be performed very easily and in a short time, and the processing accuracy can be improved. As a result, the structure 3 having a target shape can be easily obtained in a short time.

Further, since the machining accuracy is high, design data by the CAD system can be faithfully reflected on the shape of the molded body 2 by the CAM system. For this reason, even if it is not an expert who has advanced technology, the structure 3 of the target shape can be manufactured.
Furthermore, even if the metal powder contained in the green compact 1 is a difficult-to-machine material or a difficult-to-cut material powder, the machinability of the green compact 1 is hardly affected by the machinability. Therefore, the structure 3 made of difficult-to-process materials can also be easily obtained in a desired shape in a short time.

Further, in the cutting of the green compact 1, the friction generated between the green compact 1 and the processing tool 5 is very small as compared with the case where the metal material is cut. Therefore, in the present invention, it is not necessary to use cutting oil necessary for cooling the processing tool 5 and the like, and deterioration and deterioration of the metal powder due to contact with the cutting oil can be suppressed. In addition, since it is not necessary to clean the cutting oil, it is possible to reduce the manufacturing cost of the structure 3 while suppressing the environmental load.
Furthermore, since the friction generated between the green compact 1 and the processing tool 5 is small, wear of the processing tool 5 can be suppressed. For this reason, the life of the processing tool 5 is extended, and accordingly, cost reduction and high efficiency can be achieved.

<< Second Embodiment >>
Next, a second embodiment of the structure manufacturing method of the present invention will be described.
Hereinafter, although 2nd Embodiment is described, in the following description, it demonstrates centering around difference with 1st Embodiment mentioned above, The description is abbreviate | omitted about the same matter.
The present embodiment is the same as the first embodiment except that the firing step is located between the step corresponding to the primary processing step and the step corresponding to the secondary processing step. Therefore, a process corresponding to the secondary processing process of the first embodiment (a “sintered body processing process” to be described later) is not a processing process for the green compact 1, but is a sintering formed by sintering the green compact 1. This is a process for the body.

[1] Compacting Step First, the compact 1 is obtained in the same manner as in the first embodiment.
[2] Molded body processing step Next, the green compact 1 in which the molded body 2 and each connecting portion 25 are formed is obtained in the same manner as the primary processing step of the first embodiment. In the present embodiment, only the primary processing step for the green compact 1 is referred to as a molded body processing step.

[3] Firing step Next, a firing treatment is performed on the green compact 1 on which the molded body 2 and each connecting portion 25 are formed. Thereby, the green compact 1 in which the molded body 2 and each connecting portion 25 are formed reaches sintering, and a sintered body is obtained.
[4] Sintered body processing step Next, the obtained sintered body is subjected to processing similar to the secondary processing step of the first embodiment. That is, the site | part corresponded to the connection part 25 among a sintered compact is cut | disconnected and removed. Thereby, the sintered compact of the molded object 2, ie, the structure 3, is obtained.

Also in the second embodiment as described above, the portion to be processed in the sintered body processing step is a portion corresponding to the connecting portion 25 in the sintered body, which is much larger than the size of the entire sintered body. This is a part that requires only a small processing area. Therefore, since the sintered body processing step can be performed efficiently and the shape of the molded body 2 is not easily affected during processing, the sintered body (structural body 3) with high dimensional accuracy is obtained as in the first embodiment. ) Can be easily obtained.
In the second embodiment as described above, the same operations and effects as in the first embodiment can be obtained.
As mentioned above, although the manufacturing method of the molded object of this invention, the manufacturing method of a structure, and a to-be-cut material are demonstrated based on suitable embodiment, this invention is not limited to this.

Next, specific examples of the present invention will be described.
1. Production of green compact (Sample No. 1)
[1] First, a raw material of a Co—Cr—Mo—Si—N alloy was melted in a high frequency induction furnace and pulverized by a high speed rotating water atomization method to obtain a metal powder. Subsequently, classification was performed using a standard sieve having an opening of 150 μm. The alloy composition of the obtained metal powder will be described later. The alloy composition was specified by using a solid emission spectroscopic analyzer (spark emission analyzer) manufactured by SPECTRO, model: SPECTROLAB, type: LAVMB08A. For quantitative analysis of C (carbon), a carbon / sulfur analyzer, CS-200, manufactured by LECO, was used.

The composition ratio of the Co—Cr—Mo—Si—N-based alloy is such that Co is the main component, the Cr content is 26 mass% to 35 mass%, and the Mo content is 5 mass% to 12 mass. %, Si content is 0.3% by mass or more and 2.0% by mass or less, and N content is 0.09% by mass or more and 0.5% by mass or less.
Moreover, the Vickers hardness of the Co—Cr—Mo—Si—N alloy was 500, and the true density was 8.32 g / cm ³ .

[2] Next, the binder was dissolved in water to prepare a binder solution. The amount of water in the binder solution was 50 g per 1 g of binder. Moreover, polyvinyl alcohol was used as a binder. The physical properties of the used polyvinyl alcohol are as shown in Table 1.
[3] Next, the metal powder was put into the processing container of the granulator. And metal powder was rolled and granulated, spraying a binder solution from the spray nozzle of a granulator toward the metal powder in a processing container, and granulated powder (composition) was obtained.

[4] Next, the obtained granulated powder was molded under the following molding conditions to obtain a green compact. The obtained green compact was disk-shaped with a diameter of 100 mm and a thickness of 15 mm. The relative density of the green compact was 84%.
<Molding conditions>
Molding method: Press molding Molding pressure: 100 MPa (1 t / cm ² )

[5] Next, the obtained green compact was subjected to cutting (primary processing) using a 5-axis processing machine. As a result, a processing mark was formed in the green compact so that the molded body and the connecting portion shown in FIG. 3 were cut out. Note that the molded body shown in FIG. 3 can be a forceps structure used as a surgical instrument. Moreover, the work which reverses the front and back of a green compact was performed in the middle of processing. Further, no cutting oil was used in the cutting process.
The minimum cross-sectional area of the connecting portion, it was confirmed that contained in each 1 mm ² or more 10 mm ² within the following ranges.
The photograph which shows the state after giving a primary process to a green compact is shown in FIG.
[6] Next, processing (secondary processing) for cutting and removing the connecting portion was performed. Thereby, the compact as shown in FIG. 8 was separated from the green compact.

[7] Next, the machined body was degreased under the following degreasing conditions to obtain a degreased body.
<Degreasing conditions>
・ Heating temperature: 470 ° C
・ Heating time: 1 hour ・ Heating atmosphere: Nitrogen atmosphere

[8] Next, the obtained degreased body was fired under the following firing conditions to obtain a sintered body (structure) as shown in FIG.
<Baking conditions>
・ Heating temperature: 1300 ℃
Heating time: 3 hours Heating atmosphere: Argon atmosphere [9] Next, the obtained sintered body was assembled to obtain forceps (structure) as shown in FIG.
A photograph of the forceps thus obtained is shown in FIG.

(Sample Nos. 2-17)
Except that the production conditions of the green compact were changed as shown in Table 1, sample No. A forceps (structure) was obtained in the same manner as in 1. In addition, ASTM F75 described in a table | surface points out the casting material F75 of the cobalt chromium alloy in ASTM specification. Moreover, SKH51 described in the table is one type of high-speed tool steel defined in the JIS standard.

(Sample No. 18)
An ingot satisfying F75, which is an ASTM standard for a cast material of a cobalt chromium alloy, was prepared.
Next, the ingot was cut using a 5-axis machine. Thereby, a member as shown in FIG. 9A was cut out from the ingot. Note that cutting oil was used in the cutting process. Then, the machined member was washed with an organic solvent for washing.
Next, the obtained members were assembled to obtain forceps as shown in FIG.

(Sample No. 19, 20)
Except that the production conditions of the green compact were changed as shown in Table 1, sample No. A forceps (structure) was obtained in the same manner as in 1.
As described above, each sample No. Table 1 shows the manufacturing conditions of the structure.
In Table 1, those corresponding to the present invention are indicated as “Examples”, and those not corresponding to the present invention are indicated as “Comparative Examples”.

2. Evaluation of structure 2.1 Measurement of dimensional accuracy The dimensions of the structure were measured. Then, the measured dimensions were compared with the dimensions of the design data, and the dimensional accuracy was evaluated according to the following evaluation criteria.
<Evaluation criteria for dimensional accuracy>
A: Very high dimensional accuracy (deviation from design value is less than 0.2 mm)
○: High dimensional accuracy (deviation from design value: 0.2 mm or more and less than 0.5 mm)
Δ: Slightly high dimensional accuracy (deviation from design value 0.5 mm or more and less than 0.7 mm)
×: Low dimensional accuracy (deviation from design value 0.7 mm or more)

2.2 Evaluation of processing time When obtaining this structure, the time (processing time) required to cut out the compact from the green compact was determined. Next, sample no. Assuming that the time required to cut out the 16 compacts is 1, each sample No. The relative value of the time required to cut out the green body was determined. And the calculated | required relative value was evaluated in accordance with the following evaluation criteria.
<Processing time evaluation criteria>
A: Processing time is very short (relative value is less than 0.7)
○: Processing time is short (relative value is 0.7 or more and less than 0.85)
Δ: Processing time is slightly short (relative value is 0.85 or more and less than 1)
×: Processing time is long (relative value is 1 or more)

2.3 Evaluation of surface roughness of machined surface With respect to this structure, the surface roughness of the surface corresponding to the processed surface when it was cut out from the green compact was evaluated according to the following evaluation criteria.
<Evaluation criteria for surface roughness of machined surface>
A: Surface roughness is very small. O: Surface roughness is small. Δ: Surface roughness is slightly small. X: Surface roughness is large. The evaluation results of 2.1 to 2.3 are shown in Table 1.

As is apparent from Table 1, the structure manufactured by the method corresponding to the example had high dimensional accuracy. Further, the time required for manufacturing the structure was relatively short. Furthermore, it was recognized that the surface roughness of the processed surface was small and the smoothness was relatively high.
On the other hand, the structure manufactured by the method corresponding to the comparative example has low dimensional accuracy. From this, it was recognized that the dimensional accuracy of the structure to be manufactured is lowered if the relative density of the green compact is too low or too high. Further, it has been found that when a structure is cut out from an ingot, the time required for processing is very long although the dimensional accuracy is high.

DESCRIPTION OF SYMBOLS 1 ... Green compact 2 ... Molded body 3 ... Structure 5 ... Processing tool 11 ... Main surface 12 ... Main surface 21 ... Molded body 22 ... Molded body 25 ... Connection part 26 ... Processing Trace 27 …… Processing trace

Claims (7)

A compacting step of pressing a composition containing a metal powder and a binder to obtain a compact having a relative density with respect to the true density of the constituent material of the metal powder of 70% or more and 90% or less;
Processing the green compact to obtain a molded body , and
The processing step is
A primary processing step of forming a processing mark penetrating the green compact while leaving a part of the periphery of the region to be the molded body;
A secondary processing step of removing the part and separating the region from the green compact;
The manufacturing method of the molded object characterized by having.   The manufacturing method of the molded object of Claim 1 whose average particle diameters of the said metal powder are 1 micrometer or more and 15 micrometers or less.   The method for producing a molded article according to claim 1 or 2, wherein the binder contains polyvinyl alcohol having a saponification degree of 90 mol% or more and 98 mol% or less. The average value of the aspect ratio defined by S / L is 0.4 or more and 1 or less, where S is the minor axis of the metal powder particles and L is the major axis. The manufacturing method of the molded object of item. The part has a rod shape,
5. The method for manufacturing a molded body according to claim 1, wherein the partial minimum cross-sectional area is 0.2 mm 2 or more and 75 mm 2 or less.   A structure manufactured by firing the molded body obtained by the method for manufacturing a molded body according to any one of claims 1 to 5 to obtain a structure composed of a sintered metal body. Method. A compacting step of pressing a composition containing a metal powder and a binder to obtain a compact having a relative density with respect to the true density of the constituent material of the metal powder of 70% or more and 90% or less ;
Processing the green compact to form a processing mark penetrating the green compact leaving a part of the periphery of the region to be a molded body; and
Firing the green compact on which the processing marks are formed to obtain a metal sintered body;
Removing a portion corresponding to the part of the sintered metal body to obtain a structure that is a sintered body of the molded body; and
A structure manufacturing method characterized by comprising:

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